18 
Which species which are not sexually compatible can be hybridized. The 
technique involves isolating live cells of the species of ih'terest, removing 
the cell walls enzymatically, arid then either chemically or physically 
manipulating the cell contents so that the cell contents are fused 
together. Thus the genetic information of both cells is combined. The 
new, combined cell is then induced to grow in plant tissue culture. 
There are still some difficulties .to be resolved such. as inducing the 
new hybrid to grow to matdrity and inducing the growth of a new cell 
wall around the protoplasts. This is a technique, however, which 
Would permit species crossing techniques although the precision of the 
DNA recombinant molecule method is obviously not possible. 
D. SIGNIFICANCE OF THE DNA RECOMBINANT MOLECULE TECHNIQUE 
Dr. Singer emphasized that the DNA recombinant molecule research 
technique in basic research is extremely important. The technique 
permits the isolation and study of very small units of DNA corre- 
sponding to one bit of genetic information. Thus the detailed study 
of the chemical structure of the gene is now possible. Another advan- 
tage of this technique is that the researcher also can study the gene or 
units of the total DNA molecule which turn on and off the process of 
information transmittal or replication within the cell. Knowledge 
of the chemical nature cf these switches is of extreme importance and 
not readily obtained by other methods at the present time. 
Dr. Singer summarized the importance of the DNA recombinant 
molecule technique as now permitting the study of : 
(1) the structure of the individual genes; 
(2) the nature of the control mechanisms that switch genes on 
and off; and 
(3) the manner in which proteins are made in a cell. 
Potential for Agriculture 
In support of Dr. Singer’s comments about the significance of the 
DNA recombinant molecule research technique, Dr. Lewis indicated 
that agricultural scientists perceive great potential for accelerated 
research in plant and animal genetics. As he noted, there has been a 
dependence in agriculture upon improvements achieved through more 
traditional genetic methods. As he summarized these methods, he 
emphasized the gradual nature of the improvement of plant and 
animal varieties through early selection methods, then on to the more 
precise control of hybridization processes by the modem agricultural 
research scientists. All of the methods discussed by Dr. Lewis high- 
lighted the dependence upon what he refers to as essentially a sexual, 
cellular approach. He did point out, however, that even in these 
genetic methods, researchers were essentially speeding up 
natural processes and directing the selection process toward goals 
defined as advantageous for the solution of agricultural problems. 
From this level of perception, Dr. Lewis indicated that agricultural 
scientists recognize that the DNA recombinant molecule research 
technique expands considerably the range of man’s potential for 
manipulating life forms. Of particular interest is the increased capa- 
bility to provide for the transfer of characteristics which are not 
normally transmitted by sexual processes between widely separate 
species. 
[Appendix B — 68] 
